Electromagnetic coupling was originally developed to identify labels (also called tags in English language literature). To that end, an electromagnetic coupling reader comprises an electronic card equipped with an antenna capable of performing an electromagnetic coupling with an antenna of the tag so as to wirelessly power a chip disposed on the tag. The antenna of the tag then sends information present on the chip to the reader so as to identify the tag. This technology is known as RFID, an acronym for Radio Frequency IDentification. RFID technology makes it possible to create applications for access control, barcode reading, traceability of luggage, etc.
Moreover, recent developments concern using RFID technology for performing proximity transactions.
To standardize the exchanges, an NFC (Near Field Communication) standard has been created. This standard is defined by the documents ECMA 340, ETSI TS 102 190, ISO/CEI 14443 and ISO/IEC 18092 which govern protocols for modulation, coding, data transfer speeds, frame formats, as well as the initialization protocols required for collision avoidance.
With the development of NFC technology, an electromagnetic coupling reader can now detect the presence of a smartphone having a virtualization mode of a tag, also called HCE (Host Card Emulation). Thus, an electromagnetic coupling reader can control the opening of an automotive vehicle by a key integrating a tag or by a smartphone having an HCE virtualization mode.
More particularly, the invention relates to the issue of reducing the power consumption of an electromagnetic coupling reader operating in both modes of operation.
An electromagnetic coupling reader conventionally comprises:                an antenna configured to perform the electromagnetic coupling,        a management module configured to modulate and transmit an input signal on said antenna, and to demodulate and transmit an output signal received by said antenna, and        a supervision unit configured to generate said input signal and analyze said output signal in such a way as to organize a wireless communication.        
The use of a supervision unit comprising a sleep mode in which the functionalities are limited is well known in the prior art. For example, in the sleep mode the supervision unit is incapable of generating the input signal or analyzing the output signal. It follows that the [energy] consumption of the supervision unit is greatly limited in the sleep mode. Moreover, in the sleep mode, the supervision unit can be awakened by a wake-up signal connected to the management module.
A first energy saving mode consists of using a time delay on the management module to periodically awaken the supervision unit. The supervision unit then generates an input signal in order to detect the presence of an external peripheral. If no signal is received on the antenna in response to the input signal, the supervision unit concludes that no external peripheral is within range of the antenna and returns to the sleep mode.
Otherwise, a radiofrequency communication is established, for example to detect if the external peripheral has unlocking rights for an automotive vehicle. Said first energy saving mode has the advantage of detecting all peripherals: tags or smartphones having an HCE virtualization mode. However, the activation time is long for the supervision unit to generate the input signal and wait for the output signal. The result is that [energy] consumption remains significant.
To decrease consumption even more, the second energy saving mode enables the management module to periodically measure the impedance of the antenna. Indeed, a smartphone having an HCE virtualization mode can create an electromagnetic coupling on the antenna and modify the impedance of the antenna. The awakening of the supervision unit is then performed only when a smartphone having an HCE virtualization mode is actually detected by the management module. This second energy saving mode reduces consumption but does not make it possible to detect tags because their presence does not sufficiently change the impedance of the reader's antenna.
Moreover, for these two energy saving modes, there is a risk of failure of the electromagnetic coupling reader that occurs when the transmission of the wake-up signal between the management module and the supervision unit is defective. Indeed, the circuit can be physically broken or sensitive to electromagnetic disturbances.
At least one technical problem that remains is to obtain an electromagnetic coupling reader of reduced [energy] consumption, allowing the detection of a tag and a smartphone having an HCE virtualization mode, while limiting the risk of failure.